Multicamera Phase Measuring Profilometry For Accurate Depth Measurement

Structured light illumination refers to a scanning process of projecting a series of patterns such that, when viewed from an angle, a camera is able to extract range information. Ultimately, resolution in depth is controlled by the number of patterns projected which, in turn, increases the total time that the target object must remain still. By adding a second camera sensor, it becomes possible to not only achieve wrap around scanning but also reduce the number of patterns needed to achieve a certain degree of depth resolution. But a second camera also makes it possible to reconstruct 3-D surfaces through stereo-vision techniques and triangulation between the cameras instead of between the cameras and the projectors. For both of these two tasks, correspondence between points from two cameras is essential. In this paper, we develop a new method to find the correspondence between the two cameras using both the phase information generated by the temporal multiplexed illumination patterns and stereo triangulation. We also analyze the resulting correspondence accuracy as a function of the number of structured patterns as well as the geometric position of projector to cameras.